This invention relates to safety accessories for medical instruments and more particularly to a safety device for uncapping and recapping the protective sheath of a hypodermic needle.
A typical hypodermic needle or syringe has a hollow needle at one end of a cylindrical fluid container and a moveable plunger at the opposite end of the container. The plunger is used to discharge fluid from the cylinder through the needle, or to draw fluid through the needle into the cylinder.
Ideally, the syringe needle should have a relatively painless entry into the skin. Therefore it is desirable that the needle have the smallest possible cross section and that the tip of the needle be extremely sharp.
Manufacturers of syringe needles in current use have been reasonably successful in producing a needle having the desired size and tip sharpness. However, use of the syringe requires great care since even the most casual contact of the needle with the skin is likely to penetrate the skin, a circumstance commonly known as a needle stick. The term "needle stick", as used herein, refers to an unintended or accidental penetration of the skin by a hypodermic needle.
Although a needle stick is a minor injury, it carries the threat of transmitting such dangerous diseases as hepatitis and AIDS. Furthermore, potentially lethal drugs or toxins can also be accidently transmitted by a needle stick.
Due to the sharpness and delicate structure of the syringe needle, a removable protective sheath or cap, usually made of plastic, is installed over the needle. The protective sheath is an elongated sleeve, slightly longer than the needle. The sheath is closed at one end and has an opposite open end that press-fits onto the base of the needle support structure. The sheath is relatively narrow and protects the needle while permitting safe handling of the syringe when the syringe is not in use.
Before using the syringe, the protective sheath must be removed from the needle, a procedure known as uncapping. During uncapping, the sheath is normally gripped between the fingers of one hand, while the other hand holds the cylinder or main body portion of the syringe. The hand which holds the sheath is usually at greater risk in receiving a needle stick than the hand which holds the syringe. Any contact between the needle tip and the hand during the uncapping process can cause a needle stick.
After the syringe has been used, the protective sheath is often replaced over the needle, a procedure known as recapping. During recapping, the protective sheath is again held in one hand and the main body of the syringe is held in the other hand. The recapping of the sheath onto the needle is accomplished in a manner similar to the replacement of a pen cover onto a pen.
Unfortunately, any distraction, any shake of the hand, and any misalignment of the needle and sheath during recapping is likely to result in a needle stick to the hand which holds the sheath. A high risk zone around the sheath is defined as the immediate area or space surrounding the sheath where a syringe needle will pass if it is misaligned with the sheath. The hand which holds the sheath, especially the fingers are thus located in the high risk zone. Therefore the problem of needle sticks during recapping is endemic to the recapping procedure.
Anyone who has misaligned the cover of a pen with the body of a pen and contacted the hand holding the pen cover with the pen point can appreciate the likelihood of suffering a needle stick. Furthermore, uncapping and recapping the protective sheath of a syringe needle are occasions when needle sticks occur most often.
It is well known that needle sticks to the hands are the most prevalent work site accident in hospitals, physicians' offices and medical laboratories. In view of the dangerous ramifications of needle sticks it is desirable to provide a safety device for use in uncapping and recapping the protective sheath of a syringe without risk of needle sticks to the hands.